President Ray Howard said he was concerned that allocations were being made for recreational water at Green Lake, but there were no allocations even being considered for the region's premier lake, Lonsdale.

Mr Howard raised his concerns following reports last week that an investigation had been launched into a number of water tampering incidents in the Green Lake district.

The report indicated that police were appealing for information on taps being turned on at farmers' meters, while GWMWater is also investigating how 50 megalitres of water was illegally diverted into Green Lake.

GWM Water advised that it had ceased delivering water to the lake on November 22, but had been notified that the channel boards had been opened again on November 27.

Mr Howard said the flows into Green Lake had caused concerns for the Green Lake Action Group, who believed the illegal diversion could have threatened the lake's beach.

He has written a letter to GWM Water's managing director Mark Williams, seeking an explanation over why the allocation deals were made for Green Lake.

"It concerns us, statements made by the Green Lake Action Group's Glen Mibus, in his comment that they have had discussions with GWM Water last year that they wanted a beach and that they didn't want the lake full to the brim," Mr Howard said.

"Also his statement that GWM Water has been very understanding of the water level that people want at Green Lake.

"We are also concerned with a comment by your governance executive manager, Andrew Rose, that the water that was illegally averted, was earmarked for Taylors Lake to sustain the community during the rest of the summer.

"We are aware that before the last state election that the Green Lake Action Group received a commitment from the State Coalition for Green Lake to receive water if the Coalition came into office."

Mr Howard said it appeared the water was being harvested in Green Lake to improve recreational opportunities for communities in and around Horsham.

He has asked the authority whether or not the topping up of Green Lake was a directive from the state government.

"It would seem that comments by Mr Mibus that the Green Lake Action Group and GWM Water have worked in close partnership to retain water and to continually top it up, as you have only just recently completed, for the Horsham community's recreational use," he said.

"Could you please inform us whether the continual filling of Green Lake for recreational purposes is a directive of the state government, or is it a private arrangement between GWM Water and the Green Lake Action Group?"

Mr Howard said it was totally unfair for communities in and around Horsham to continue receiving water, particularly when it is was being taken from Lake Lonsdale.

"Could you please explain to our community why GWM Water deprives us of recreational water by continually draining Lake Lonsdale," Mr Howard said.

"It is not only an insult to the community of the greater Stawell region, but also shows a total disregard for our community's businesses and tourist operators.

"Lake Lonsdale is the premier lake of the Wimmera region and has a very significant roll in promoting tourism in the Grampians.

"We are also aware that recently, Minister Hugh Delahunty announced a huge grant for the recreation area of Green Lake and also the millions plus dollars that have been spent on recreational facilities not only at Green Lake, but also Taylors Lake and the Wimmera River at Horsham.

"While Lake Lonsdale has for years been neglected, except to recently install a breakwater for safe boating reasons. We offer you the opportunity to inform our community of these concerns."

GWM Water spokeswoman Helen Friend said the authority was continuing to maintain a focus on water security heading towards summer.

Ms Friend she GWM Water was aware of the concerns raised by Mr Howard and the Lake Lonsdale Action group and would work towards ensuring a satisfactory outcome for all.